Make the sauce: In a food processor or a blender,
place sorrel, yogurt, garlic, 2 tablespoons olive oil, the mustard and
salt to taste; process until it is bright green. Taste and add salt, if
desired. Refrigerate until needed.

Cut woody white stalks from chard leaves. Bring a
large pan of water to boil. Add the stalks and simmer for 4 minutes.
Then add the leaves, stir and continue simmering for 3 minutes. Drain
the chard and allow to cool slightly. Once cool enough to handle,
squeeze out as much water as possible. Chop leaves and stalks roughly
and put in a medium bowl.

In a small skillet, fry pine nuts in 1 tablespoon
olive oil for 1 minute, or until light brown. Add nuts and oil to the
chard, followed by the cheese, egg, bread crumbs, 1/4 teaspoon salt and
pepper to taste. If mixture is very soft and sticky, add more crumbs.

Pour enough frying oil into a large skillet to come
1/4 inch up the sides. Shape chard mixture into eight patties roughly 2
inches in diameter and 5/8-inch thick. Fry them for about 3 minutes on
each side, or until golden brown. Place on paper towels to absorb oil.
Serve warm or at room temperature, with sauce on the side.